The proposed research is divided into three groups of interrelated experiments that are directed toward furthering our understanding of the neurobehavioral basis of the rewarding effects of ethanol. The first of these is designed to determine if ethanol will cause changes in the threshold for rewarding brain stimulation (electrodes in the medial forebrain bundle-lateral hypothalamic area) in the rat and if these changes are a relevant model for ethanol induced euphoria or "high". In these experiments the effects of ethanol will be compared to those of a benzodiazepine, a barbiturate and Delta9-THC. Also the effects of ethanol in combination with each of these drug will be determined. Similarly the effects of naloxone on ethanol induced changes in responding for brain-stimulation reward will be investigated. The second group of experiments is designed to determine if ethanol effects on the threshold for rewarding brain stimulation are related to the specific area of the brain that is being stimulated. Brain sites to be compared are those that are relatively high or low in either norepinephrine, dopamine or acetylcholine. The third group of experiments will determine the effects of ethanol on the threshold for detection of stimulation (using brain stimulation as a cue) from the same brain sites studied in the experiments above. Since changes in detection threshold are probably related to changes in attentional and cognitive processes, while changes in reward threshold are probably related to changes in motivational and emotional processes, these two procedures will allow for a direct comparison of the effects of ethanol on these two functional systems and their putative underlying neuronal substrates.